The present invention relates to circular saw blades used to cut expansion grooves in concrete areaways or the like. The cut grooves are then filled with a compression sealant of neoprene or other similar synthetic rubberlike material which allows the grooves to function as expansion joints in response to temperature induced expansion or contraction.
The current state of the art of expansion joints indicates a preference for a two tier joint that is commonly made in two cutting steps. The first step involves the cutting of a narrow groove to a predetermined depth. This is followed by the cutting of a second wider groove cut to a lesser depth above the narrow groove. This wider and shallower groove receives the compression seal material. The two cutting step approach has an obvious disadvantage in that after the first cut is made the blade must be changed to a smaller diameter and wider blade before the second cut can be made. An example of this approach is shown in U.S. Pat. No. 4,456,303.
The prior art as exemplified by L. H. Metzger U.S. Pat. No. 3,127,837 disclosed an early attempt at a saw blade assembly capable of cutting a two tier groove in a single pass of the blade over the concrete. The saw blade assembly disclosed comprised a composite blade body including a pair of outside cutting disks and a central inside spacer and routing disk. The central spacer and routing disk is of larger diameter then the diameter of the outer cutting disks with the diameter of the outer disks being equal. This three blade construction as disclosed was a complicated and expensive blade assembly.
Russian patent 259,124 discloses a "Road Surface Cutter" for making seams in the hardened surfaces of roads, airfields, etc. that produces a stepped seam in one cut. The disclosed cutter comprises a circular blade body or core having a thick, metal, center disk portion and a thin rim surrounding the center disk portion. The perimeter of the disk portion on each side of the rim is covered with rings of cutting material, the rings being made of metallic matrix with abrasive matter such as diamond fragments embedded therein. There appears to be little provision for protecting the core against premature wear in critical areas caused by abrasive particle buildup during the sawing operation.
It is an object of the present invention to provide a saw blade of relatively simple construction that would enable a two tier expansion joint to be cut efficiently in a single pass over a paved areaway.
More particularly it is an object of the present invention to provide a saw blade in which the saw blade assembly includes a single circular blade body or core of uniform thickness having a plurality of spaced cutting elements secured to the periphery of the blade body and also having a plurality of spaced cutting blocks arranged in a circular configuration on the blade body intermediate the periphery and the blade center whereby a two tier expansion groove is automatically cut in a single pass over the paved area.
It is a further object of the present invention to provide a saw blade that has provision for the flow of coolant over and around the cutting elements and cutting blocks thereby to increase the cutting life of the blades and to allow the cutting speed of the blade to be increased.
These and other objects of the invention will be apparent from the following disclosure of preferred embodiments thereof.